As is known in the art, quadrature couplers are used in a variety of microwave circuits to split an input signal into a pair of output signals, usually with equal magnitudes, that are ninety degrees apart in phase. Examples of such quadrature couplers are an embedded stripline broadside coupler or a topside quadrature coupler, such as a Lange or hybrid (branchline) splitter. One use of quadrature couplers is to impedance match pairs of devices. The devices are arranged so that reflections from them are terminated in a load that is isolated from the quadrature coupler's input because of the 90 degree (quadrature) phase difference.
As is also known in the art, prior art quadrature couplers are integrated into a larger board that has many functions. As such, the design such as the degree of coupling, is not easy alterable.